In modern life, the circuit breaker is definitely a decisive circuit device, and it is one of the most important safety mechanisms in domestic circuits. Once the current flow in the house wiring is too large, such a simple circuit device will cut off the power until the fault is eliminated. If there is no circuit breaker, household electricity will be very inconvenient. What is the function of the circuit breaker? What are the circuit breaker models ? If you are interested in this, you might as well take a look at the circuit breaker models with me!
Breaker Introduction
Circuit breakers are capable of closing, carrying, and breaking currents under normal circuit conditions and are capable of engaging, switching, and breaking electrical currents under abnormal circuit conditions for a specified period of time. Circuit breakers generally consist of a contact system, an arc extinguishing system, an operating mechanism, a trip unit, a housing, and the like. Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. The division of high and low voltage boundary lines is relatively vague, and circuit breakers above 3 kV are generally called high-voltage electrical appliances.
Circuit Breaker Features
1. Multi-oil circuit breakers are simple to implement and inexpensive, but they are generally not used because of the large amount of oil used, their large size, the large amount of overhaul work, and their prone to explosion and fire.
2, less oil circuit breaker with less oil, the tank structure is small and strong, with the saving of materials, explosion-proof fire characteristics. The use of a low-oil circuit breaker makes the power distribution unit greatly simplified, small in size, easy to transport, and widely used at present.
3, air circuit breakers have large breaking capacity, fast action time, small size, light weight, no fire risk, but the structure is complex, the price is expensive, need to install compressed air system, etc., mainly used for 110KV and above on the electrical parameters and open circuit time There are higher requirements in the system.
4, SF6 good electrical performance, fracture voltage can be higher. The equipment is easy to operate, maintain and overhaul, has a long overhaul period, and it has good breaking performance and small footprint. In particular, the development of SF6-enclosed combination appliances can greatly reduce the area occupied by substations. SF6 circuit breakers are widely used in the 1990s. At present, China has successfully produced and developed SF6 circuit breakers of 220, 330, and 500 kV.
Circuit breaker model meaning
At present, China's high-voltage circuit breaker model according to the provisions of national technical standards, generally composed of text symbols and numbers in the following manner. Its representative significance is:
1—The product letter code, represented by the following letters: S—Less oil circuit breakers; D—Multi oil circuit breakers; K—Air circuit breakers; L—Sulfur hexafluoride circuit breakers; Z—Vacuum circuit breakers; Q—Production gas Circuit breaker; C-magnetic blower circuit breaker.
2—Location code of the device; N—indoor, W—outdoor.
3—Design series serial number; represented by numbers 1, 2, 3...
4—Rated voltage, KV.
5 - Other supplementary work characteristic marks, G - improved type, F - phase separation operation.
6-rated current, A.
7—rated breaking current, KA.
8-Specific environment code.
High voltage circuit breaker model
DW series high pressure outdoor installation multi oil circuit breaker;
SW series high pressure outdoor installation oil circuit breaker;
SN series high pressure indoor installation of low oil circuit breakers;
ZW series high pressure outdoor installation vacuum circuit breaker;
ZN series high voltage indoor installation vacuum circuit breaker;
LW series high pressure outdoor installation SF6 circuit breaker;
LN series high voltage indoor install SF6 circuit breaker;
Low-voltage circuit breaker model
DW10 series frame automatic switch;
DWX15, DWX15C series universal current limiting circuit breaker;
DW17 (ME) series universal circuit breaker;
DZ10 series plastic shell type automatic switch;
DZ15 series plastic shell circuit breaker;
DZX10 series plastic shell current limiting circuit breaker;
DZ20 series plastic shell circuit breaker;
DZ25 series plastic shell circuit breakers.
The function of the circuit breaker
Circuit breaker is also called air switch. Its role is to cut off and connect the load circuit, and cut off the fault circuit to prevent accidents from expanding and ensure safe operation. In the case of electrical overload or abnormal operation, if there is a failure, the circuit breaker will automatically open the switch to protect the electrical equipment and the circuit. In addition, the circuit breaker has a leakage protection device and has the function of leakage protection.
Circuit breakers can be used to distribute electrical energy, start asynchronous motors infrequently, and protect power lines and motors. When they are severely overloaded or short-circuited or under-voltage faults, the circuit breaker can automatically shut off the circuit. Its function is equivalent to The combination of a fuse switch and an over-heat relay, etc., does not normally require changing parts after breaking the fault current.
Circuit breaker working principle
The working principle of the circuit breaker is that when a short circuit occurs, a magnetic field generated by a large current overcomes the reaction force spring, and the tripping device pulls the action of the operating mechanism and the switch trips instantaneously. When overloaded, the current increases and the heat is increased. The bimetal deforms to a certain degree and pushes the mechanism. The greater the current, the shorter the operating time. The circuit breaker is of the electronic type, and transformers are used to collect the current of each phase. Compared with the set value, the microprocessor sends a signal when the current is abnormal, and the electronic trip unit drives the operating mechanism.
Low-voltage circuit breaker working principle
The main contacts of the low-voltage circuit breaker are manually operated or electrically closed. After the main contact is closed, the free tripping mechanism locks the main contact in the closing position. The coil of the overcurrent release and the thermal element of the thermal release are connected in series with the main circuit and the coil of the undervoltage release is connected in parallel with the supply. When the circuit is short-circuited or severely overloaded, the armature of the over-current release pulls in, causing the free tripping mechanism to act, and the main contact opens the main circuit. When the circuit is overloaded, the thermal element of the thermal release heats up to bend the bimetal and push the free tripping mechanism. When the circuit is under voltage, the armature of the undervoltage release releases. The free trip mechanism is also actuated. The shunt release is used for remote control. In normal operation, the coil is powered off. When distance control is required, press the start button to energize the coil.
Circuit breaker parameters
The following parameters are generally used to characterize the basic operating performance of high voltage circuit breakers:
1, the rated voltage (nominal voltage)
It is a parameter that characterizes the insulation strength of the circuit breaker. It is the standard voltage for long-term operation of the circuit breaker. In order to meet the requirements of power system work, circuit breakers also specify the maximum operating voltage corresponding to the rated voltage at all levels. For 3-220KV levels, the maximum operating voltage is approximately 15% higher than the rated voltage; for 330KV and above, the maximum operating voltage is approximately 10% higher than the rated voltage. Circuit breakers should work reliably for a long time under the highest working voltage.
2, rated current
It is a parameter that characterizes the ability of a circuit breaker to pass long-term current, that is, the maximum current that the circuit breaker allows for continuous long-term passage.
3, rated breaking current
It is a parameter that characterizes the breaker breaking capacity. Under the rated voltage, the maximum current that the circuit breaker can guarantee to break reliably is called the rated breaking current, and the unit is expressed by the kiloampere number of the effective value of the periodic component of the transient short circuit current of the circuit breaker contact. When the circuit breaker operates in a grid below its rated voltage, its breaking current can increase. However, due to the limitation of the mechanical strength of the arc extinguishing chamber, the breaking current has a maximum value, which is called the limiting breaking current.
Editor's summary: The above is the introduction of the model and parameters of high and low voltage circuit breakers. I hope to help friends who have this need! For more information, please continue to pay attention to our website, follow-up will show more exciting content. You can also purchase your favorite product on Qijia Mall!
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